Low-fat or 'light' foods encourage over-eating in the long-term

By Niamh Michail contact

- Last updated on GMT

© iStock
© iStock

Related tags: Nutrition, Obesity

Low-fat, light and diet versions of products may actually contribute to rising obesity rates by encouraging over consumption compared to regular products both in the short- and long-term, Dutch scientists have found.

In response to the burgeoning global obesity crisis, the World Health Organisation (WHO) has called for public policies that promote low-fat, high-fibre foods, and the food industry has responded: low-fat products are now big business. According to figures from Transparency Market Research, the global low-calorie food market was worth about €6.5 billion in 2013.

But such a policy may backfire both in the short- and long-term, according to a study by Dutch researchers published in International Journal of Research in Marketing​.

While previous studies have confirmed consumers’ tendencies to overconsume low-fat foods for single occasions - perceived to be less dangerous to long-term health goals - not enough research has looked at whether this trend is also true in the long-term.

The researchers suggest low-fat products may encourage consumers to adjust the amount of food they buy upwards, across categories, even for regular products.

“These results confirm the experimentally known short-term effect that low-fat choices increase food consumption. Importantly, our results also show a significant positive long-term effect. This suggests that the overconsumption effect is persistent.”

They added: “Beyond the fact that we observe a persistent over-purchasing effect using actual behavioural data, our findings also provide more support for the over-generalisation of claim effects and habit formation resulting in the enduring effect of healthy food choices. Beyond that, we show that this effect solely occurs due to the over-consumption of low-fat products, while no increase in regular product consumption is found."

“In the end, it seems that consumers and society are worse off, as the first low-fat purchase increases food consumption and calorie intake. Hence, instead of reducing the obesity problem, low-fat products may enhance this problem in the long run.”

Policymakers should be careful in embracing low-fat products as a solution to the obesity crisis, although they concede that the psychological mechanisms at play can be complex and commonly unconscious.

The study

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The researchers used data from the Dutch GfK household scanner data which provides information on purchasing behaviour, product-specific health claims and calorie information, as well as market information on advertising by the companies.

They focused on chips as this category offers many low-fat versions. A total of 311 households that first purchased low-fat crisps between 2004 and 2007 were included.

Purchase histories of all the households were pooled one year before and one year after the first low-fat purchase.

They found households “significantly​” increased the amount of chips purchased in the first month after the initial purchase, as well as in long-term purchase volumes.

An interesting area for future research would be to test whether the same results are found for a 'virtue' product, such as yoghurt, they say, as well as looking at other health claims beyond ‘low-fat’.

Source: International Journal of Research in Marketing

Published online ahead of print 13 May 2016, available here

“Regular or low fat? An investigation of the long-run impact of the first low-fat purchase on subsequent purchase volumes and calories”

Authors: Kathleen Cleeren, Kelly Geyskens, Peter Verhoef, Joost Pennings

Related topics: R&D

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